The Tissue Culture Core will support tissue culture activities in Project 1, Project 3, and Project 4. (Project 2 will use rat liver, and Project 5 will use intact transgenic animals). This Core will optimize the use of the extensive tissue culture expertise that has accumulated in this unit over the last 18 years. It will provide a central facility for obtaining and testing the quality of materials required for tissue culture by the investigators in this Program Project. The materials will include Fetal Bovine Serum (FBS), which is tested for consistency and then ordered in large enough amounts so that a single lot of FBS will support the activities of the Program Project for at least one year. New tissue culture plasticware will also be tested for problems by the Core before being used more widely within the Program Project laboratories. The Core will provide started cultures, and when requested, will prepare cultures for specific experiments. There will be a charge to the investigators for each culture; this fee is designed to encourage optimal use of tissue cultures from the core. Cells will be grown in the core by meticulous methods using well- standardized protocols. Inside the protocol for the fibroblasts has now been published (APPENDIX). These procedures provide a high degree of standardization of fibroblast cultures by biological age in culture (CPDL), as well as meticulous control of other aspects of tissue culture such as mycoplasma testing. Tumor cells, including PC12 cells, will be grown by techniques that we have already standardized in this laboratory. Where necessary, this core will also prepare primary neuron-enriched or glial- enriched cultures. The experience of the core will facilitate the use of other cell types for any of the PROJECTS. The Tissue Culture Core is designed to augment tissue culture facilities in the laboratories of the specific investigators. it will provide optimal support for the tissue culture needs of the individual investigators, while leaving each investigator in full control of the cultures needed for their investigation.